Printer using print cartridge with internal pressure regulator

ABSTRACT

In the preferred embodiment, an inkjet printer includes a replaceable print cartridge which is inserted into a scanning carriage. An ink tube extends from the scanning carriage to a separate ink supply located within the printer. A fluid interconnect on the print cartridge connects to a fluid interconnect on the carriage when the print cartridge is inserted into the carriage to complete the fluid connection between the external ink supply and the print cartridge. In one embodiment, the fluid interconnection is made between the print cartridge and the ink tube simply by placing the print cartridge into a stall in the scanning carriage. A pressure regulator internal to the print cartridge regulates the flow of ink from the external ink supply to the print cartridge. The external ink supply may be pressurized or non-pressurized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/550,902, filed Oct. 31, 1995, entitled "Apparatus forProviding Ink to an Ink-Jet Print Head and for Compensating forEntrapped Air" by Norman Pawlowski, Jr. et al., attorney docket No.1094910, which is a continuation-in-part of U.S. patent application Ser.No. 08/518,847, filed Aug. 24, 1995, entitled "Pressure RegulatedFree-Ink Ink-Jet Pen," by Norman Pawlowski, Jr. et al., now U.S. Pat.No. 5,736,992, which is a continuation-in-part of U.S. patentapplication Ser. No. 08/331,453, filed Oct. 31, 1994, by NormanPawlowski, Jr. et al., know U.S. Pat. No. 5,583,545.

This is also a continuation-in-part of U.S. application Ser. No.08/429,915, filed Apr. 27, 1995, entitled "Ink Supply for an Ink-JetPrinter," by James Cameron et al., attorney docket no. 1094053-2.

This application is also a continuation-in-part of U.S. patentapplication Ser. No. 08/566,821, filed Dec. 4, 1995, entitled"Self-Sealing Fluid Interconnect with Double Sealing Septum," by JohnBarinaga et al., attorney docket no. 10951195.

FIELD OF THE INVENTION

This invention relates to inkjet printers and, more particularly, to aninkjet printer having a scanning printhead with a stationary ink supply.

BACKGROUND OF THE INVENTION

Inkjet printers are well known. One common type of inkjet printer uses areplaceable print cartridge which contains a printhead and a supply ofink contained within the print cartridge. The print cartridge is notintended to be refillable and, when the initial supply of ink isdepleted, the print cartridge is disposed of and a new print cartridgeis installed within the scanning carriage. Frequent replacement of theprint cartridge results in a relatively high operating cost.

The printhead has a useable life which is significantly longer than thetime it takes to deplete the ink within the print cartridge. It is knownto refill print cartridges intermittently by creating an opening throughthe print cartridge and manually refilling the print cartridge with ink.However, these refilling methods require manipulation by the user andare undesirable for various other reasons.

It is also known to provide an external, stationary ink reservoirconnected to the scanning print cartridge via a tube; however, thesetypes of printing systems have various drawbacks including undesirablefluctuations in ink pressure in the print cartridge, an unreliable andcomplex fluid seal between the print cartridge and the external inksupply, increased printer size due to the external ink supply'sconnection to the print cartridge, blockage in the ink delivery system,air accumulation in the tubes leading to the print cartridge, leakage ofink, high cost, and complexity.

What is needed is an improved inkjet printer with a replaceable printcartridge and a separate ink delivery system connectable to the printcartridge.

SUMMARY

In the preferred embodiment, an inkjet printer includes a replaceableprint cartridge which is inserted into a scanning carriage. An ink tubeextends from the scanning carriage to a separate ink supply locatedwithin the printer. A fluid interconnect on the print cartridge connectsto a fluid interconnect on the carriage when the print cartridge isinserted into the carriage to complete the fluid connection between theexternal ink supply and the print cartridge. In one embodiment, thefluid interconnection is made between the print cartridge and the inktube simply by placing the print cartridge into a stall in the scanningcarriage. A pressure regulator, which may be internal or external to theprint cartridge, regulates the flow of ink from the external ink supplyto the print cartridge. The external ink supply may be pressurized ornon-pressurized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of one embodiment of an inkjet printerincorporating the present invention.

FIG. 1B is a top down view of another inkjet printer incorporating thepresent invention.

FIG. 2 is a perspective view of the ink delivery system and carriage ofanother embodiment inkjet printer incorporating the present invention.

FIG. 3A illustrates the preferred carriage with one embodiment of theprint cartridge in cross-section.

FIG. 3B is a perspective view looking down on a carriage with one printcartridge installed.

FIG. 3C illustrates the use of a flexible tube connected to a rigidelbow member and to a manifold.

FIG. 3D is a top down view of a carriage incorporating the flexible tubeof FIG. 3C.

FIG. 3E is a top down view of a carriage without a manifold andincorporating a flexible tube connected to a rigid elbow member.

FIG. 3F is a perspective view of a carriage without a manifold andincorporating a flexible tube connected to a rigid elbow member.

FIG. 4 is a detailed view of the interface between the flexible tubesconnected to the external ink supply and the fluid interconnect locatedon the carriage.

FIG. 5A is a perspective view of the preferred print cartridge and thefluid interconnect portion of the carriage.

FIG. 5B is another perspective view of the preferred print cartridge andfluid interconnect of the carriage.

FIG. 5C is a cross-sectional view of the print cartridge of FIG. 5B nowconnected to the fluid interconnect on the carriage.

FIG. 6 is a simplified front view of the print head assembly on apreferred print cartridge.

FIG. 7 is a perspective view of the back side of the printhead assembly.

FIG. 8 is a cross-sectional view of the portion of the print cartridgecontaining the printhead assembly showing the flow of ink to the inkejection chambers in the printhead.

FIG. 9A is a perspective view of a scanning carriage incorporating fourprint cartridges in accordance with another embodiment of the invention.

FIG. 9B is an ink supply station having ink supply cartridges installedtherein in accordance with one embodiment of the invention.

FIG. 10 is a perspective view of another embodiment print cartridge.

FIG. 11A is a side view of the print cartridge of FIG. 10 connected to afluid interconnect on the scanning carriage.

FIG. 11B illustrates a replaceable ink supply cartridge about to engagethe ink refill port on the print cartridges of FIGS. 10 and 11A inanother embodiment printer.

FIG. 12A is a side view of the carriage of FIG. 9A.

FIG. 12B is a side view in partial cross-section of the ink supplystation in FIG. 9B.

FIG. 12C is a detailed view of the fluid interconnect portion located onthe ink supply station for connection to an ink supply cartridge.

FIG. 13 is a perspective view of the two parts making up the manifold inthe ink supply station.

FIG. 14 is a perspective view of the two parts making up the manifold inthe scanning carriage.

FIG. 15 is a partial cutaway view of a print cartridge in accordancewith another embodiment of the invention.

FIGS. 16 and 17 illustrate the interconnection between the fluidinterconnect on the print cartridge of FIG. 15 and the fluidinterconnect on the scanning carriage.

FIG. 18 is a perspective view in partial cross-section of the printcartridge of FIG. 15 illustrating an ink pressure regulator which may beinternal to any of the print cartridges described herein.

FIG. 19 is a perspective view of the pressure regulator sub-assembly ofthe print cartridge of FIG. 18 without the flexible air bag.

FIG. 20 is a perspective view of a pressure regulator lever in thepressure regulator sub-assembly of FIG. 19.

FIG. 21 is a perspective view of the opposite side of the pressureregulator lever of FIG. 20.

FIG. 22 is a perspective view of an accumulator lever of the pressureregulator sub-assembly of FIG. 19.

FIG. 23 is a perspective view of a fitment for the print cartridge ofFIG. 18.

FIG. 24 is a perspective view of the flexible bag and fitment for theprint cartridge of FIG. 18.

FIGS. 25 through 30 are diagrammatic views of the process for making theflexible bag of FIG. 24.

FIG. 31 is a perspective view of the crown for the print cartridge ofFIG. 18.

FIG. 32 is a perspective view, partially cut away, of the crown andpressure regulator of FIG. 19 with the accumulator removed.

FIGS. 33 through 35 are side elevation views in partial cross-sectionillustrating the operation of the print cartridge of FIG. 18.

FIG. 36A is an exploded view of a non-pressurized ink supply cartridge.

FIG. 36B is a cross-sectional view of a pressurized ink bag which mayuse the housing shown in FIG. 36A.

FIG. 36C is one embodiment of a spring used to provide a positivepressure on the ink bag in FIG. 36B.

FIG. 37 is an exploded view of an ink supply in accordance with oneembodiment of the present invention.

FIG. 38 is a cross-sectional view, taken along line 38--38 of FIG. 37,of a portion of the ink supply of FIG. 37.

FIG. 39 is a side view of the chassis of the ink supply of FIG. 37.

FIG. 40 is a bottom view of the chassis of FIG. 39.

FIG. 41 is a top perspective view of the pressure plate of the inksupply of FIG. 37.

FIG. 42 is a bottom perspective view of the pressure plate of FIG. 41.

FIG. 43 is an exploded, cross-sectional view of an alternativeembodiment of a pump for use in an ink supply in accordance with thepresent invention.

FIG. 44 shows the ink supply of FIG. 37 being inserted into a dockingbay of an inkjet printer.

FIG. 45 is a cross-sectional view of a part of the ink supply of FIG. 37being inserted into the docking bay of an inkjet printer, taken alongline 45--45 of FIG. 44.

FIG. 46 is a cross-sectional view showing the ink supply of FIG. 45fully inserted into the docking bay.

FIG. 47 shows the docking bay of FIG. 44 with a portion of the dockingbay cutaway to reveal an out-of-ink detector.

FIGS. 48A through 48E are cross-sectional views of a portion of the inksupply and docking bay showing the pump, actuator, and out-of-inkdetector in various stages of operation, taken along line 48--48 of FIG.47.

FIG. 49 is a perspective view of a facsimile machine showing oneembodiment of the ink delivery system in phantom outline.

FIG. 50 is a perspective view of a copier, which may be a combinedfacsimile machine and printer, illustrating one embodiment of the inkdelivery system in phantom outline.

FIG. 51 is a perspective view of a large-format inkjet printerillustrating one embodiment of the ink delivery system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Overview of Printer Embodiments

FIG. 1A is a perspective view of one embodiment of an inkjet printer 10,with its cover removed, incorporating various inventive features.Generally, printer 10 includes a tray 12 for holding virgin paper. Whena printing operation is initiated, a sheet of paper from tray 12 is fedinto printer 10 using a sheet feeder, then brought around in a Udirection to now travel in the opposite direction toward tray 12. Thesheet is stopped in a print zone 14, and a scanning carriage 16,containing one or more print cartridges 18, is then scanned across thesheet for printing a swath of ink thereon.

After a single scan or multiple scans, the sheet is then incrementallyshifted using a conventional stepper motor and feed rollers 20 to a nextposition within print zone 14, and carriage 16 again scans across thesheet for printing a next swath of ink. When the printing on the sheetis complete, the sheet is forwarded to a position above tray 12, held inthat position to ensure the ink is dry, and then released.

Alternative embodiment printers include those with an output traylocated at the back of printer 10, where the sheet of paper is fedthrough the print zone 14 without being fed back in a U direction.

The carriage 16 scanning mechanism may be conventional and generallyincludes a slide rod 22, along which carriage 16 slides, and a codedstrip 24 which is optically detected by a photodetector in carriage 16for precisely positioning carriage 16. A stepper motor (not shown),connected to carriage 16 using a conventional drive belt and pulleyarrangement, is used for transporting carriage 16 across print zone 14.

The novel features of inkjet printer 10 and the other inkjet printersdescribed in this specification relate to the ink delivery system forproviding ink to the print cartridges 18 and ultimately to the inkejection chambers in the printheads. This ink delivery system includesan off-axis ink supply station 30 containing replaceable ink supplycartridges 31, 32, 33, and 34, which may be pressurized or atatmospheric pressure. For color printers, there will typically be aseparate ink supply cartridge for black ink, yellow ink, magenta ink,and cyan ink.

Four tubes 36 carry ink from the four replaceable ink supply cartridges31-34 to the four print cartridges 18.

Various embodiments of the off-axis ink supply, scanning carriage, andprint cartridges will be described herein.

FIG. 1B is a top down view of another printer 10 very similar to thatshown in FIG. 1A, but with the paper tray removed. An electricalconnector 37 is shown connected between printer 10 and a personalcomputer. Elements throughout the various figures identified with thesame numerals may be identical.

FIG. 2 illustrates the ink delivery system of an alternative embodimentprinter 40. In this embodiment, four replaceable ink supply cartridges42-45 are shown installed in a fixed station 46 above a scanningcarriage 48. This particular location of station 46 and the horizontalarrangement of ink supply cartridges 42-45 results in an efficientutilization of available space within printer 40. In another embodiment,station 46 may be located virtually anywhere within printer 40.

A single print cartridge 50 is shown installed in carriage 48. Fourtubes 36, each connected to an ink supply cartridge 42-45, are in fluidconnection with a rubber septum 52 for each of the four stalls incarriage 48. A hollow needle 60 (FIG. 3A) formed as part of each printcartridge 50 is inserted through the rubber septum 52 upon pushing theprint cartridge 50 into its associated stall within carriage 48 so thata fluid communication path exists between a particular ink supplycartridge 42-45 and a particular print cartridge 50 for providing asupply of ink to the print cartridge 50.

A sheet of paper enters through the bottom portion of printer 40 in thedirection of arrow 53, then guided back in a U direction, andtransported through the print zone 14 in the direction of arrow 54.Carriage 48 then scans across print zone 14 for printing on the sheet.In another embodiment, a sheet of paper enters the print zone 14 in thedirection of arrow 53.

Elements previously designated and described will not be redundantlydescribed.

Description of Carriage and Print Cartridge Embodiments

FIG. 3A is a perspective view looking up at carriage 48, showing printcartridge 50 and septum 52 in cross-section. This cross-section does notshow a regulator valve within print cartridge 50 that regulates pressureby opening and closing hole 65. An opening in the bottom of carriage 48exposes the printhead location 58 of each print cartridge 50. Carriageelectrodes 49 oppose contact pads located on print cartridge 50.

When the aforementioned regulator valve is opened, a hollow needle 60 isin fluid communication with an ink chamber 61 internal to printcartridge 50. The hollow needle 60 extends through a self-sealing slitformed through the center of septum 52. This self-sealing slit isautomatically sealed by the resiliency of the rubber septum 52 whenneedle 60 is removed.

A plastic ink conduit 62 leads from needle 60 to ink chamber 61 via hole65. Conduit 62 may also be integral to the print cartridge body. Conduit62 may be glued, heat-staked, ultrasonically welded, or otherwisesecured to the print cartridge body.

Ink is provided to carriage 48 by tubes 36 which connect to a plasticmanifold 66. Tubes 36 may be formed of Polyvinylidene Chloride (PVDC),such as Saran™, or other suitable plastic. Tubes 36 may also be formedof a very flexible polymer material and dipped in PVDC for reducing airdiffusion through the tubes. In the preferred embodiment,non-pressurized ink tubes 36 have an internal diameter betweenapproximately 1.5-2.5 mm, while pressurized ink tubes 36 have aninternal diameter between approximately 1-1.5 mm. Manifold 66 providesseveral 90° redirections of ink flow. Such a manifold 66 may not beneeded if tubes 36 are sufficiently slender and can be bent withoutbuckling. A pressurized off-axis ink supply (described later) mayutilize such slender tubing. An alternative to manifold 66 is a seriesof elbows molded or formed out of heat formed tubing.

A septum elbow 71 routes ink from manifold 66 to septum 52 and supportsseptum 52. Septum 52 is affixed to elbow 71 using a crimp cap 73.

A bellows 67 (shown in cross-section) is provided for each of theindividual stalls 68 for allowing a degree of x, y, and z movement ofseptum 52 when needle 60 is inserted into septum 52 to minimize the x,y, and z load on needle 60 and ensure a fluid-tight and air-tight sealaround needle 60. Bellows 67 may be formed of butyl rubber, high acnnitrile, or other flexible material with low vapor and air transmissionproperties. Bellow 67 can be any length and can even be a flexiblediaphram.

A spring 70 urges septum 52 upward. This allows septum 52 to take up ztolerances, minimizes the load on needle 60, and ensures a tight sealaround needle 60.

Slots 72 formed on each of the stalls 68 in carriage 48 align with tabson each print cartridge 50 to restrict movement of the print cartridge50 within the stall 68.

An air vent 74 formed in the top of print cartridge 50 is used by apressure regulator in print cartridge 50, to be described later. In analternative embodiment, a separate regulator may be connected betweenthe off-axis ink supply and each print cartridge 50.

FIG. 3B is a perspective view of carriage 48 looking down on carriage 48and showing one print cartridge 50 installed.

In other embodiments, shown in FIGS. 3C-3F, bellows 67 is replaced witha U-shaped, circular, or straight flexible tube.

FIG. 3C illustrates a circular flexible tube 63 connected between elbow71 and manifold 66.

FIG. 3D is a top down view of the carriage 16 incorporating tube 63.

In another embodiment, shown in FIG. 3E, manifold 66 is deleted, andtubes 63 are connected to (or are part of) tube 36. A plastic guide 64may be used to guide the tubes 63.

In FIG. 3F, the tubes 36 are directly connected to the rigid plasticelbow 71 supporting septum 52 without being coiled.

If desired, the print cartridges can be secured within the scanningcarriage by individual latches, which may be manually operated or springloaded, where the latches press down on a tab or a corner of the printcartridge. In another embodiment, a single latch, such as a hinged bar,secures all four print cartridges in place within the carriage.

FIG. 4 is a detailed view of manifold 66, tubes 36, crimp cap 73, septum52, septum elbow 71, spring 70, and bellows 67 described with respect toFIG. 3A. A stress reliever 77 for tubes 36 is also shown.

FIG. 5A is a perspective view of one embodiment of print cartridge 50. Ashroud 76 (also shown in FIG. 3B) surrounds needle 60 (obscured byshroud 76) to prevent inadvertent contact with needle 60 and also tohelp align septum 52 (FIG. 3A) with needle 60 when installing printcartridge 50 in carriage 48.

Coded tabs 79 align with coded slots in the carriage stalls 68 to ensurethe proper color print cartridge 50 is placed in the proper stall 68. Inanother embodiment, coded tabs 79 are located on shroud 79.

A flexible tape 80 containing contact pads 86 leading to the printheadsubstrate is secured to print cartridge 50. These contact pads 86 alignwith and electrically contact electrodes 49 (FIG. 3A) on carriage 48.Preferably, the electrodes on carriage 48 are resiliently biased towardprint cartridge 50 to ensure a reliable contact. Such carriageelectrodes are found in U.S. Pat. No. 5,408,746, entitled DatumFormation for Improved Alignment of Multiple Nozzle Members in aPrinter, by Jeffrey Thoman et al., assigned to the present assignee andincorporated herein by reference.

The printhead nozzle array is at location 58. An integrated circuit chip78 provides feedback to the printer regarding certain parameters ofprint cartridge 50.

FIG. 5B illustrates the bottom side of print cartridge 50. Two parallelrows of offset nozzles 82 are shown laser ablated through tape 80. Anink fill hole 81 is used to initially fill print cartridge 50 with ink.A stopper (not shown) is intended to permanently seal hole 81 after theinitial filling.

FIG. 5C is a cross-sectional view of print cartridge 50, without tape80, taken along line 5C--5C in FIG. 5A. Shroud 76 is shown having aninner conical or tapered portion 75 to receive septum 52 and centerseptum 52 with respect to needle 60. In an alternative embodiment,needle 60 is part of a separate subassembly, and shroud 76 is a separatesubassembly, for manufacturing ease and to allow color key changing bychanging the shroud, assuming the color key tabs are located on theshroud.

The print cartridges and ink supply connections described thus far aredown-connect types where the ink connection is made when pressing theprint cartridge down into the carriage. This enables a resulting printerto have a very low profile since the ink path does not extend above theprint cartridge. In various embodiments shown having the needleextending from the print cartridge, the needle may be replaced with aseptum, and the septum on the scanning carriage replaced with a hollowneedle.

FIGS. 6, 7, and 8 illustrate the basic principles of the printheadassembly 83. Printhead assembly 83 is preferably a flexible polymer tape80 (FIG. 5B) having nozzles 82 formed therein by laser ablation.Conductors 84 (FIG. 7) are formed on the back of tape 80 and terminatein contact pads 86 for contacting electrodes on carriage 48. The otherends of conductors 84 are bonded through windows 87 to terminals of asubstrate 88 (FIG. 7) on which are formed the various ink ejectionchambers and ink ejection elements. The ink ejection elements may beheater resistors or piezoelectric elements. The printhead assembly maybe similar to that described in U.S. Pat. No. 5,278,584, by Brian Keefe,et al., entitled "Ink Delivery System for an Inkjet Printhead," assignedto the present assignee and incorporated herein by reference. In such aprinthead assembly, ink within print cartridge 50 flows around the edgesof the rectangular substrate 88 and into ink channels 90 leading to eachof the ink ejection chambers.

FIG. 8 illustrates the flow of ink 92 from the ink chamber 61 withinprint cartridge 50 to ink ejection chambers 94. Energization of the inkejection elements 96 and 98 cause a droplet of ink 101, 102 to beejected through the associated nozzles 82. A photoresist barrier layer104 defines the ink channels and chambers, and an adhesive layer 106affixes the flexible tape 80 to barrier layer 104. Another adhesive 108provides a seal between tape 80 and the plastic print cartridge body110. In one embodiment, a wall 112 separates the ink flow paths aroundthe two edges of substrate 88, and a different color ink is supplied toeach side of wall 112.

The conductor portion of the flexible tape 80 is glued or heat-staked tothe print cartridge body 110.

A demultiplexer on substrate 88 demultiplexes the incoming electricalsignals applied to contact pads 86 and selectively energizes the variousink ejection elements to eject droplets of ink from nozzles 82 asprinthead 79 scans across the print zone. In one embodiment, the dotsper inch (dpi) resolution is 300 dpi, and there are 300 nozzles 82. Inanother embodiment, at least the black ink cartridge prints at aresolution of 600 dpi.

FIG. 9A is a perspective view of another embodiment scanning carriage120 having four print cartridges 122-125 installed. One of the printcartridges 122 is shown in FIG. 10. Tubes 36 from an off-axis ink supplystation 128 (FIG. 9B) supply ink to a manifold 130 which redirects theink to a 90° interface cap 132 for each of print cartridges 122-125.Preferably, each cap 132 is of a color similar to the color ink withineach print cartridge 122-125. This embodiment differs from that shown inFIG. 3A in that the ink is coupled to print cartridges 122-125 bypressing a septum 133 (FIG. 11) down onto a hollow needle 134 (FIG. 10)extending from the top of the print cartridge 122, rather than pressinga needle 60 (FIG. 3A) down into the septum 52 (FIG. 3A). Also shown inFIG. 10 are air vent 74 for an internal pressure regulator, coded tabs135 for ensuring the proper color print cartridge is installed in theproper carriage stall, and the location 58 of the printhead.

In the particular embodiment shown in FIG. 9B, only three out of thefour color ink supply cartridges 136-139 are installed in ink supplystation 128. A hollow needle 142 extending from a stall in the inksupply station 128, to be described in greater detail with respect toFIGS. 12B and 12C, is in fluid communication with one of tubes 36. Theink within each of ink supply cartridges 136-139 is at atmosphericpressure, and ink is drawn into each of print cartridges 122-125 by anegative pressure within each print cartridge 122-125 determined by aregulator internal to each print cartridge.

In another embodiment, to be described later, the off-axis ink supplycartridges are pressurized. In both the pressurized and unpressurizedink supply embodiments, the regulator internal to each print cartridgeregulates the pressure of ink supplied to the print cartridge.

In another embodiment, shown in FIG. 11B, the print cartridges 122installed in carriage 120 have ink supply cartridges 139 connecteddirectly to needle 134, so that carriage 120 supports the printcartridges 122 and the ink supply cartridges 139. A septum on the inksupply cartridges 139 connect to needle 134 in a manner similar to thatshown in FIG. 11A. The ink supply cartridges 139 are preferably made tohave a low profile to achieve a low profile printer.

FIG. 12A is a side view of the carriage 120 and print cartridge assemblyof FIG. 9A connected to the off-axis ink supply station 128 via tubes36.

FIG. 12B is a cross-sectional view of ink supply cartridge 138 in theoff-axis ink supply station 128 taken along line 12B--12B in FIG. 9B. Asseen, a hollow needle 142 extending in an upward direction from the inksupply support 144 is inserted through a rubber septum 146 on ink supplycartridge 138 to create a fluid communication path between the inkreservoir 148 within ink supply cartridge 138 and one ink conduit withinmanifold 150. In one embodiment, ink reservoir 148 comprises acollapsible ink bag, to be described later. The ink conduits withinmanifold 150 are coupled to tubes 36 which connect to the various printcartridges within scanning carriage 120.

FIG. 12C is a detailed view of needle 142 extending from the ink supplystation 128. Also shown are a spring-loaded humidor 145, having a rubberportion 145' which covers needle hole 147 when the ink supply cartridge138 is removed, and a plastic elbow 149 connected to tube 36. Elbows 149replace manifold 150 (FIG. 12B) in the embodiment of FIG. 12C.

FIG. 13 is a perspective view of manifold 150 in the off-axis ink supplystation 128 of FIG. 12B. Manifold 150 is opened to reveal the internalink conduits 152-155.

FIG. 14 is a perspective view of the four ink conduits 156 in manifold130 on the scanning carriage 120 of FIG. 9A for redirecting the flow ofink from tubes 36 to print cartridges 122-125 in FIG. 9A.

FIG. 15 is perspective view of another embodiment print cartridge 158 inpartial cross-section.

Print cartridge 158 of FIG. 15 may be similar to any one of printcartridges 122-125 shown in FIG. 9A except that, instead of having aneedle protruding from a top surface of the print cartridge, printcartridge 158 has a rubber septum 160 for receiving a hollow needle.Print cartridge 158 is to be installed in a carriage similar to carriage120 in FIG. 9A. An axial passage 162 communicates between a central slitformed in septum 160 and an ink chamber 164 within print cartridge 158.A cap 166 is crimped onto neck 168 and onto septum 160 to form a sealbetween septum 160 and the remainder of the print cartridge 158. Thecrimping of cap 166 also serves to compress septum 160 so as to ensurethe central slit is sealed.

The flexible tape 80 forming a part of the printhead assembly is shownrevealed on a side of print cartridge 158. Contact pads 86 forconnection to electrodes on a carriage are also shown.

FIG. 16 illustrates the fluid interconnect between an ink supply tube 36and septum 160 of print cartridge 158. Tube 36, connected to an off-axisink supply, is fitted over a hollow needle 170. Needle 170 is preferably18-gage stainless steel having a diameter of about 1.2 mm. A housing 172on the scanning carriage houses a spring 174 and a sliding humidorconsisting of a rigid plastic collar 176 and a compliant inner portion178. A pocket 180 in the compliant inner portion 178 reduces thefriction between the compliant inner portion 178 and needle 170. In FIG.16, print cartridge 158 is installed in the carriage prior to the fluidinterconnect being made.

FIG. 17 shows the completed fluid interconnect between the off-axis inksupply and print cartridge 158 after the fluid interconnect system onthe carriage has been brought down onto print cartridge 158. Thedownward force of the fluid interconnect system compresses spring 174while causing needle 170 to be inserted through a central slit in septum160. The compliant inner portion 178 and rubber septum 160 are incontact with one another. Ink now flows from the off-axis ink supplystation, through tube 36, through hollow needle 170, through hole 182formed in hollow needle 170, through axial passage 162, and into theprint cartridge's ink chamber 164 (FIG. 15).

In another embodiment, needle 170 directly extends from a replaceableink supply cartridge, such as from ink supply cartridge 139 in FIG. 11B,and the ink supply cartridge and print cartridges 158 are supported bythe scanning carriage.

The central slit formed in septum 160 creates an air-tight seal aroundneedle 170. The slit becomes sealed when needle 170 is withdrawn fromseptum 160.

Print cartridge 158 is thus supplied with ink from the off-axis inksupply station.

Thus, a number of print cartridge embodiments and ink interconnectionsbetween an off-axis ink supply and the print cartridge have been shown.

Description of Regulator Internal to Print Cartridges

FIGS. 18-35 describe a pressure regulator which may be used within anyof the print cartridge embodiments described herein for regulating thepressure of the ink chamber within the print cartridge. Hence, thepressure in the off-axis ink supply system may be unregulated. Theregulator causes the ink chamber within the print cartridge to have aslight, but substantially constant, negative pressure (e.g., -2 to -7inches of water column) to prevent ink drool from the nozzles of theprinthead. If the off-axis ink supply system is at atmospheric pressure,this slight negative pressure in the print cartridge also acts to drawink from the off-axis ink supply system even if the location of the inksupply system is slightly below the print cartridge. The regulator alsoenables the use of pressurized off-axis ink supplies while maintainingthe desired negative pressure within the ink chamber in the printcartridge. The regulator can be designed to provide a wide range ofnegative pressures (or back pressures) from 0 to -50 inches of watercolumn, depending on the design of the printhead.

In the embodiments shown in FIGS. 18-35, the regulator is described withreference to the type of print cartridge similar to print cartridge 158in FIG. 15 having a septum 235 (FIG. 18); however, it is to beunderstood that a regulator using similar concepts may also be used withany of the other print cartridge embodiments.

Referring to FIG. 18, reference numeral 214 generally indicates theprint cartridge that includes a pen body 242 that is the housing for thecartridge and a crown 243 that forms a cap to the housing. Located at aremote end of the pen body is the tab head assembly 244 or THA. The THAincludes a flex circuit 245 and a silicon die 246 that forms the printhead 240. The THA is of conventional construction. Also located withinthe pen body 242 is a pressure regulator lever 248, an accumulator lever250, and a flexible bag 252. In FIG. 18, the bag is illustrated fullyinflated and for clarity is not shown in FIG. 19. The pressure regulatorlever 248 and the accumulator lever 250 are urged together by a spring253, 253' illustrated in FIG. 19. In opposition to the spring, the bagspreads the two levers apart as it inflates outward. The bag is stakedto a fitment 254 that is press-fit into the crown 243. The fitmentcontains a vent 255 to ambient pressure in the shape of a helical,labyrinth path. The vent connects and is in fluid communication with theinside of the bag so that the bag is maintained at a reference pressure.The helical path limits the diffusion of water out of the bag.

The pressure regulator lever 248 is illustrated in detail in FIGS. 20and 21. Reference numeral 257 generally indicates the location of thearea where the bag 252 directly bears against the lever. The lever 248rotates about two opposed axles 258 that form the axis of rotation ofthe lever. The rotation of the lever is stopped when the lever engagesthe pen body 242 as illustrated in FIG. 35. The axles are located at theends of cantilevers 259 formed by deep slots so that the cantilevers andthe axles can be spread apart during manufacture and snapped onto placeon the crown 243 as illustrated in FIG. 32. Perpendicular to the planeof the regulator lever 248 is a valve seat 261 and a valve seat holder262. The valve seat is pressed into place on the holder and isfabricated from a resilient material. In response to expansion andcontraction of the bag 252, the regulator lever 248 rotates about theaxles 258, 258' and causes the valve seat to open and shut against amating surface on the crown 243 as described below. This rotationalmotion controls the flow of ink into the ink plenum 238, FIG. 34. Thereis an optimization between maximizing the force on the valve seat andobtaining sufficient motion of the lever. In the embodiment actuallyconstructed, the lever ratio between the distance between the centroidof the lever, generally at point 257, and the axles 258 and the distancebetween the center of the valve seat and the axles 258 is between two toone and five to one with four to one being preferred. The pressureregulator also includes a spring boss 264 and engages the spring 253,FIG. 19. The spring boss is protected during manufacture by twoshoulders 265 which are not illustrated in FIG. 19.

The accumulator lever 250 is illustrated in FIG. 22 and includes anactuation area 268 where the bag 252 directly bears against the lever.The lever rotates about two opposed axles 270, 270' that form an axis ofrotation of the accumulator lever. The axles are remotely located oncantilevers 271 so that the axles and the cantilevers can be spreadapart during manufacture and snapped into place on the crown 243 asdescribed below. The accumulator lever also includes a spring boss 272that engages the other end of the spring 253, FIG. 19. Like the springboss 64 on the pressure regulator, the boss 272 on the accumulator isprotected during manufacture by the shoulders 273. These shoulders arenot illustrated in FIG. 19.

The accumulator lever 250 and the bag 252 operate together toaccommodate changes in volume due to any air that may be entrapped inthe print cartridge 214, as well as due to any other pressure changes.The accumulator acts to modulate any fluctuations in the back pressure.The accumulator lever squeezes the bag the inside of which is at ambientpressure, forces air out of the bag and allows air trapped in the printcartridge to expand.

Although most of the accumulation is provided by the movement of theaccumulator lever 250 and the bag 252, there is additional accumulationprovided by the pressure regulator lever 248 in cooperation with theresilient valve seat 261, FIG. 20. The valve seat acts as a spring andallows some movement of the regulator lever 248 while the valve is shut.In other words, as the back pressure in the plenum 238 (FIG. 34)decreases, the bag 252 exerts less force on the levers, and the spring253 urges the levers together. The motion of the regulator levercompresses the valve seat and the regulator lever shuts a littlefurther. This movement of the regulator lever 248 with the bag 252results in some additional air accommodation.

It should be appreciated that the boss 272 on the accumulator lever 250is closer to the axis of rotation of the accumulator lever than the boss264, FIGS. 20 and 21, on the pressure regulator lever is to its axis ofrotation. This difference in distance causes the accumulator lever toactuate before the pressure regulator lever moves.

The accumulator lever 250 rotates about the axles 270 until a stop 275on the lever engages a surface 276 within the crown 243, as illustratedin FIG. 31. The stop prevents the lever from moving too close andinterfering with the pressure regulator lever 248 when the back pressurein the ink plenum drops. The accumulator lever rotates in the otherdirection until coming into contact with the pen body 242 as illustratedin FIGS. 34 and 35.

Referring to FIG. 19, reference numeral 253 generally indicates ahelical extension spring that urges the two levers 248, 250 together.The spring is preloaded and engages the bosses 264, 272 with a coil loopat each distal end. Each loop is a parallel, cross-over, fully closed,centered loop. This spring is designed to have the least amount ofvariation in its force constant over its full range of travel so thatthe back pressure can be regulated as closely as possible.

The fitment 254, illustrated in FIGS. 18 and 23, supports the bag 252and attaches the bag to the crown 243. The fitment has a lip 278 thatengages the crown and forms a hermetic seal with it. Within the fitmentis a vent 255 that provides communication between the interior of thebag and ambient pressure. At the distal end of the fitment is a raised,circular boss 279 and a race-track shaped outer boss 280. The bag 252 isstaked to both bosses. The circular boss provides the main seal betweenthe bag and the fitment. The race-track shaped boss provides asecondary, redundant sealing surface as well as provides additionalsupport and positioning for the bag.

The flexible bag 252, illustrated in FIGS. 18 and 24, expands andcontracts as a function of the differential pressure between the backpressure in the ink plenum 238 (FIG. 34) and ambient pressurecommunicated through the vent 255 in the fitment 254. The bag is shownfully inflated in FIG. 24. The bag is designed to push against the twolevers 248, 250 with maximum contact area through the entire range oftravel of the levers. The bag is formed from a single sheet ofmultilayer film and includes two lungs 282 that expand and contractabout an axis 284. The lungs communicate with each other and aremaintained at the same reference pressure. Each lung has two raisedareas 283 on either side so that there are four raised areas in all. Thetwo inner raised areas that bear against each other are not shown inFIG. 24 but are indicated by reference numerals 283' and 283". The sideopposite the fitment contains a raised communication channel 285, FIGS.26, 28, between the raised areas which allows a path for air to flowwhen the bag is completely deflated. The raised areas are thinner thatthe rest of the bag and provide greater compliance to the travel of thelevers and the motion of the lungs about the axis 284. The raised areasare designed to eliminate relative motion or sliding of the bag withrespect to the levers. In systems that actuate on very slight pressures,this undesirable affect is called hysteresis. The combination of thelungs and raised areas provides extra material into which the bag canexpand as well as maximizes the change in ink volume displaced by thebag with any change in differential pressure.

The process for making the bag 252 is illustrated in FIGS. 25-30. First,a sheet 287 of flat film is cut to size, FIG. 25. The film is amultilayer structure between one and three mils (one rail is 25.4microns) thick, 1.5 mils being the preferred thickness. In the preferredembodiment, three materials show acceptable performance: (1)PE/tie/PVDC/tie/PE, (2) PE/tie/PVDF/tie/PE, and (3) PE/tie/EVOH/tie/PE.PVDC is polyvinylidene chloride; DOW version is known as SARAN. EVOH isethylene-vinyl alcohol copolymer. PE is polyethylene. Tie is a layerused to bond the dissimilar materials together. PVDF ispolyvinylidenefluoride and is sold under the trade name of Kynar™. Next,the sheet is placed over a die plate, and heat and vacuum are applied toform the four raised areas 288, 288', FIG. 26. Note that two of the fourraised areas or pockets 288' are in communication. Thereafter, the sheet287 is heat staked to the two bosses 279, 280 on the fitment 254, FIG.23, as shown in FIG. 27. Next, a hole 289 is made in the film in thecenter of the circular boss 279 to establish communication to the vent255 in the fitment. The sheet is then folded along axis 290 and theperimeter of the bag where the margins came together is staked. Thisstaking occurs along the three open seams and is indicated by referencenumeral 291 in FIG. 29. The perimeter of the bag is then trimmed.Thereafter, the bag is folded along the longitudinal axis 296 of thefitment as illustrated in FIG. 29. This forms the two lungs 282, 282' inthe bag. Referring to FIGS. 29, 30, and 24, the longitudinal axis 296 ofthe fitment and the line of folding in FIG. 29 is parallel to the axis284 of rotation of the two lungs including expansion/contraction of thebag.

FIG. 31 illustrates the bottom-side of the crown 243 which includes avalve face 293 and the tapered nozzle or orifice 292 through which inkenters the plenum 238. The valve face mates with the valve seat 261,FIG. 20, on the pressure regulator lever 248. This mating is also shownin FIG. 32. Ink flows through the fluid interconnect, the septum 235,and the orifice 292. The tapered orifice 292 reduces the area of contactbetween the valve seat 261 and the valve face 293 to thereby increasethe valve sealing pressure.

At orifice 292, the back pressure within the plenum 238 (FIG. 34) iscontrolled by the lever 248. Next to the valve face 293 on the crown 243is a circular boss 294 that receives the lip 278 on the fitment 254,FIG. 24. The boss 294 and the lip form a hermetic seal. The axles 258,258', FIG. 21, on the pressure regulator lever 248 are snapped into thejournals 295, 295' as permitted by the cantilevered constructiondescribed above. In like manner the axles 270, 270' on the accumulatorlever 250 are received in the journals 297, 297', FIG. 31. Also locatedon the bottom side of the crown is the surface 276 that engages the stop275, FIG. 22, on the accumulator lever 250. The stop 275 and the surface276 prevent the accumulator lever from interfering with the pressureregulator lever 248.

The operation of the print cartridge 214 is illustrated in FIGS. 33, 34,and 35. In the initial condition of the cartridge, there is no inkwithin the ink plenum 238, and the bag 252 is limp. The back pressure inthe plenum equals ambient pressure. The spring 253 urges the two levers248, 250 fully together.

Next, a hollow needle is inserted into the septum 235 and a vacuum isdrawn on the nozzles in the print head 240 (FIG. 18) to draw ink intothe print cartridge. In response to this vacuum, the accumulator lever250 moves first, and the bag begins to expand as shown in FIG. 24. Theaccumulator lever continues to rotate about its axis of rotation untilit engages the side wall of the pen body 242 as shown in FIG. 24. Atthis point the pressure regulator lever 248 begins to move, and inkbegins to enter the plenum 238 through orifice 292, FIG. 31.

The regulator lever 248 can rotate about its axis of rotation until itengages the side wall of the pen body 242 as shown in FIG. 35. This isthe full-open position of the valve. The regulator lever moves betweenthe states illustrated in FIGS. 34 and 35 depending on the speed ofprinting and how fast ink is required by the print head.

Once the plenum 238 is filled with ink or printing has stopped, thepressure regulator lever 248 will slowly rotate and close the orifice atthe urging of the spring 253. The levers 248 and 250 return to the stateillustrated in FIG. 34 which is the normal or steady state condition ofthe print cartridge. This state occurs just prior to or subsequent toprinting.

Referring to FIG. 34, reference numeral 298 indicates an air bubble thathas entered the ink plenum 238. If the print cartridge is subjected toan elevation in temperature or increased altitude, the air bubble willexpand in the plenum. The expansion of the air bubble will becompensated for by the contraction of the bag 252 due to a pressurechange caused by a volume change of the bubble which in turn causes theaccumulator lever to move from the state illustrated in FIG. 34 towardthat illustrated in FIG. 33. In addition, there will be someaccompanying motion of the regulator lever 248 because of the resilienceof the valve seat 261. On the other hand, if the air bubble contracts,the bag will expand in response and the pressure regulator lever 248will open the orifice and admit ink onto the plenum. In other words, anyexpansion or contraction of an air bubble will cause the bag tocompensate in reverse, that is by contracting to expansion and expandingto contraction. Each of the levers tracks the motion of the bag and theaccumulator lever 250 rotates before the regulator lever 248 because ofthe difference in lever arm distances.

When the off-axis ink supply (e.g., supply 30 in FIG. 1) is depleted ofink, the levers 248, 250 rotate to the full-open position in FIG. 35 andthe print head stops ejecting ink.

Description of the Off-Axis Ink Delivery System

FIG. 36A is an exploded view of a non-pressurized ink supply cartridge300 such as shown in FIGS. 2, 9B, and 12B. Such an ink supply cartridge300 is simply removed from the ink supply support (e.g., support 144 inFIG. 12B) and disposed of once its supply of ink has been depleted. Theconnection of such an ink supply cartridge 300 to the fluid interconnecthas been described with respect to FIG. 12B.

The non-pressurized ink supply cartridge 300 consists of a collapsibleink bag 302 and two rigid plastic housing members 303 and 304. Ink bag302 may be formed of a flexible film such as Mylar or EVA, or amulti-layer film similar to the plastic sheet 350 described with respectto FIG. 37 or the nine-layer film described in U.S. Pat. No. 5,450,112,assigned to the present assignee and incorporated herein by reference.The ends of inkbag 302 may be heat-staked or ultrasonically welded tohousing member 303 or 304 to limit movement of bag 302.

Coded tabs 305 align with slots formed in the ink supply support toensure the proper color ink supply cartridge is inserted into thecorrect stall of the ink supply support. In one embodiment, the inksupply support also latches onto tab 305, using a spring-loaded latch,to secure cartridge 300 and to provide tactile feedback to the user thatcartridge 300 is properly installed.

A plastic ink bag fitment 306 is partially inserted through an opening307 in ink bag 302 and sealed with respect to opening 307 by glue orheat fusing. A poppet 308 extends from fitment 306. Bag fitment 306 isheld firmly in place by a slot 307 formed in the plastic housing members303 and 304.

A poppet spring 309 is inserted through a hole 310 in poppet 308followed by a poppet ball 311. Ball 311 may be stainless steel orplastic.

An end 312 of a rubber septum 313 is then inserted into hole 310 inpoppet 308. Septum 313 is then crimped and secured to poppet 308 using acrimped cap 314.

Septum 313 has a slit 315 formed through its center through which ahollow needle 142 (FIG. 12B), in fluid connection with a printcartridge, is inserted as shown in FIG. 12B. Slit 315 in septum 313 isautomatically urged closed by the resiliency of septum 313 when theneedle is removed.

Poppet spring 309 and poppet ball 311 serve to provide added assurancethat no ink will leak through slit 315 in septum 313. When there is noneedle inserted through slit 315, poppet spring 309 urges poppet ball311 against the closed slit 315 so that ball 311 in conjunction with theclosing of slit 315 provides a seal against ink leakage. Furtherdescription of this type of double-sealing valve is provided withrespect to the pressurized ink supply cartridge embodiment shown in FIG.37.

It is possible to design the fluid interconnect using a septum withoutthe poppet, or a poppet without the septum. A septum without the poppetwill reliably seal around a needle with a radial seal. However, when theink supply with a septum has been installed in the printer for a longtime, the septum will tend to take on a compression set. Upon removal,the septum may not completely reseal itself. If the supply is tipped ordropped, ink may leak out. A poppet valve (by itself) has the advantage(relative to a septum) of self-sealing without a compression set issue.However, it is less reliable in that it does not seal around the needle.Thus, to ensure a leak-tight fluid interconnection with the cartridge,some kind of face seal must be established. In addition, poppet valvesvary in reliability when the surface they seal against is hardplastic--small imperfections in the sealing surface tend to lead toleaks. The combination of the septum/poppet valve overcomes theselimitations by utilizing the advantages of both: the septum's very goodsealing around the needle while eliminating the compression set issue.Additionally, the inside surface of the septum provides a compliantsealing surface for the poppet valve that is less sensitive toimperfections.

In the preferred embodiment, an integrated circuit sensor/memory 316 ispermanently mounted to ink supply cartridge 300. This circuit provides anumber of functions, including verifying insertion of the ink supply,providing indication of remaining ink in the supply, and providing acode to assure compatibility of the ink supply with the rest of thesystem.

In an alternate embodiment, ink bag 302 is provided with a positivepressure. This enables the tubes connecting the ink supply to the printcartridges to be thinner and also allows the ink supply station to belocated well below the print cartridges. FIG. 36B is a cross-sectionalview of ink supply cartridge 300 along line 36B--36B in FIG. 36Aillustrating how a spring 317 urges the sides of ink bag 302 together tocreate a positive internal pressure. Ink bag 302 is provided with rigidside panels 318 to distribute the spring force. Bow springs, spiralsprings, foam, a gas, or other resilient devices may supply the springforce. Ink 319 is shown within ink bag 302. FIG. 36C is a top down viewof one embodiment of spring 317 formed as a stainless steel spiral.

In another embodiment, ink bag 302 may be pressurized by an intermittentpressure source, such as a gas.

FIGS. 37-48E illustrate a pressurized off-axis ink supply cartridge andan apparatus for pressurizing the ink supply cartridge.

FIG. 37 is an exploded view of ink supply 320.

The ink supply 320 has a chassis 322 which carries an ink reservoir 324for containing ink, a pump 326, and fluid outlet 328. The chassis 322 isenclosed within a hard protective shell 330 having a cap 332 affixed toits lower end. The cap 332 is provided with an aperture 334 to allowaccess to the pump 326 and an aperture 336 to allow access to the fluidoutlet 328.

To use the ink supply 320, it is inserted into a docking bay 338 of anink-jet printer, as illustrated in FIGS. 1 and 44-47. Upon insertion ofthe ink supply 320, an actuator 340 within the docking bay 338 isbrought into contact with the pump 326 through aperture 334. Inaddition, a fluid inlet 342 within the docking bay 338 is coupled to thefluid outlet 328 through aperture 336 to create a fluid path from theink supply to the printer. Operation of the actuator 340 causes the pump326 to draw ink from the reservoir 324 and supply the ink through thefluid outlet 328 and the fluid inlet 342 to the printer.

Upon depletion of the ink from the reservoir 324, or for any otherreason, the ink supply 320 can be easily removed from the docking bay338. Upon removal, the fluid outlet 328 and the fluid inlet 342 areclosed to help prevent any residual ink from leaking into the printer oronto the user. The ink supply may then be discarded or stored forreinstallation at a later time. In this manner, the present ink supply320 provides a user of an ink-jet printer a simple, economical way toprovide a reliable and easily replaceable supply of ink to an ink-jetprinter.

As illustrated in FIGS. 37-40, the chassis 322 has a main body 344.Extending upward from the top of the chassis body 344 is a frame 346which helps define and support the ink reservoir 324. In the illustratedembodiment, the frame 346 defines a generally square reservoir 324having a thickness determined by the thickness of the frame 346 andhaving open sides. Each side of the frame 346 is provided with a face348 to which a sheet of plastic 350 (FIG. 37) is attached to enclose thesides of the reservoir 324. The illustrated plastic sheet is flexible toallow the volume of the reservoir to vary as ink is depleted from thereservoir. This helps to allow withdrawal and use of all of the inkwithin the reservoir by reducing the amount of back pressure created asink is depleted from the reservoir. The illustrated ink supply 320 isintended to contain about 30 cubic centimeters of ink when full.Accordingly, the general dimensions of the ink reservoir defined by theframe are about 57 millimeters high, about 60 millimeters wide, andabout 5.25 millimeters thick. These dimensions may vary depending on thedesired size of the ink supply and the dimensions of the printer inwhich the ink supply is to be used.

In the illustrated embodiment, the plastic sheets 350 are heat staked tothe faces 348 of the frame in a manner well known to those in the art.The plastic sheets 350 are, in the illustrated embodiment, multi-plysheets having an outer layer of low density polyethylene, a layer ofadhesive, a layer of metallized polyethylene terephthalate, a layer ofadhesive, a second layer of metallized polyethylene terephthalate, alayer of adhesive, and an inner layer of low density polyethylene. Thelayers of low density polyethylene are about 0.0005 inches thick and themetallized polyethylene terephthalate is about 0.00048 inches thick. Thelow density polyethylene on the inner and outer sides of the plasticsheets can be easily heat staked to the frame while the double layer ofmetallized polyethylene terephthalate provides a robust barrier againstvapor loss and leakage. Of course, in other embodiments, differentmaterials, alternative methods of attaching the plastic sheets to theframe, or other types of reservoirs might be used.

The body 344 of the chassis 322, as seen in FIGS. 37-40, is providedwith a fill port 352 to allow ink to be introduced into the reservoir.After filling the reservoir, a plug 354 (FIG. 38) is inserted into thefill port 352 to prevent the escape of ink through the fill port. In theillustrated embodiment, the plug is a polypropylene ball that is pressfit into the fill port.

A pump 326 is also carried on the body 344 of the chassis 322. The pump326 serves to pump ink from the reservoir and supply it to the printervia the fluid outlet 328. In the illustrated embodiment, seen in FIGS.37 and 38, the pump 326 includes a pump chamber 356 that is integrallyformed with the chassis 322. The pump chamber is determined by askirt-like wall 358 which extends downwardly from the body 344 of thechassis 322.

A pump inlet 360 is formed at the top of the chamber 356 to allow fluidcommunication between the chamber 356 and the ink reservoir 324. A pumpoutlet 362 through which ink may be expelled from the chamber 356 isalso provided. A valve 364 is positioned within the pump inlet 360. Thevalve 364 allows the flow of ink from the ink reservoir 324 into thechamber 356 but limits the flow of ink from the chamber 356 back intothe ink reservoir 324. In this way, when the chamber is depressurized,ink may be drawn from the ink reservoir, through the pump inlet and intothe chamber. When the chamber is pressurized, ink within the chamber maybe expelled through the pump outlet.

In the illustrated embodiment, the valve 364 is a flapper valvepositioned at the bottom of the pump inlet. The flapper valve 364illustrated in FIGS. 37 and 38, is a rectangular piece of flexiblematerial. The valve 364 is positioned over the bottom of the pump inlet360 and heat staked to the chassis 322 at the midpoints of its shortsides (the heat staked areas are darkened in the Figures). When thepressure within the chamber drops sufficiently below that in thereservoir, the unstaked sides of the valve each flex downward to allowthe flow of ink around the valve 364, through the pump inlet 360 andinto the chamber 356. In alternative embodiments, the flapper valvecould be heat staked on only one side so that the entire valve wouldflex about the staked side, or on three sides so that only one side ofthe valve would flex. Other types of valves may also be suitable.

In the illustrated embodiment the flapper valve 364 is made of a two plymaterial. The top ply is a layer of low density polyethylene 0.0015inches thick. The bottom ply is a layer of polyethylene terephthalate(PET) 0.0005 inches thick. The illustrated flapper valve 364 isapproximately 5.5 millimeters wide and 8.7 millimeters long. Of course,in other embodiments, other materials or other types or sizes of valvesmay be used.

A flexible diaphragm 366 encloses the bottom of the chamber 356. Thediaphragm 366 is slightly larger than the opening at the bottom of thechamber 356 and is sealed around the bottom edge of the wall 358. Theexcess material in the oversized diaphragm allows the diaphragm to flexup and down to vary the volume within the chamber. In the illustratedink supply, displacement of the diaphragm allows the volume of thechamber 356 to be varied by about 0.7 cubic centimeters. The fullyexpanded volume of the illustrated chamber 356 is between about 2.2 and2.5 cubic centimeters.

In the illustrated embodiment, the diaphragm 366 is made of the samemulti-ply material as the plastic sheets 350. Of course, other suitablematerials may also be used to form the diaphragm. The diaphragm in theillustrated embodiment is heat staked, using conventional methods, tothe bottom edge of the skirt-like wall 358. During the heat stakingprocess, the low density polyethylene in the diaphragm seals any foldsor wrinkles in the diaphragm to create a leak proof connection.

A pressure plate 368 and a spring 370 are positioned within the chamber356. The pressure plate 368, illustrated in detail in FIGS. 41 and 42,has a smooth lower face 372 with a wall 374 extending upward about itsperimeter. The central region 376 of the pressure plate 368 is shaped toreceive the lower end of the spring 370 and is provided with a springretaining spike 378. Four wings 380 extend laterally from an upperportion of the wall 374. The illustrated pressure plate is molded ofhigh density polyethylene.

The pressure plate 368 is positioned within the chamber 356 with thelower face 372 adjacent the flexible diaphragm 366. The upper end of thespring 370, which is stainless steel in the illustrated embodiment, isretained on a spike 382 formed in the chassis and the lower end of thespring 370 is retained on the spike 378 on the pressure plate 368. Inthis manner, the spring biases the pressure plate downward against thediaphragm to increase the volume of the chamber. The wall 374 and wings380 serve to stabilize the orientation of the pressure plate whileallowing for its free, piston-like movement within the chamber 356. Thestructure of the pressure plate, with the wings extending outward fromthe smaller face, provides clearance for the heat stake joint betweenthe diaphragm and the wall and allows the diaphragm to flex withoutbeing pinched as the pressure plate moves up and down. The wings arealso spaced to facilitate fluid flow within the pump.

An alternative embodiment of the pump 326 is illustrated in FIG. 43. Inthis embodiment, the pump includes a chamber 356a defined by a skirtlikewall 358a depending downwardly from the body 344a of the chassis. Aflexible diaphragm 366a is attached to the lower edge of the wall 358ato enclose the lower end of the chamber 356a. A pump inlet 360a at thetop of the chamber 356a extends from the chamber 356a into the inkreservoir and a pump outlet 362a allows ink to exit the chamber 356a.The pump inlet 360a has a wide portion 386 opening into the chamber356a, a narrow portion 388 opening into the ink reservoir, and ashoulder 390 joining the wide portion 386 to the narrow portion 388. Avalve 364a is positioned in the pump inlet 360a to allow the flow of inkinto the chamber 356a and limit the flow of ink from the chamber 356aback into the ink reservoir. In the illustrated embodiment the valve iscircular. However, other shaped valves, such as square or rectangular,could also be used.

In the embodiment of FIG. 43, a unitary spring/pressure plate 392 ispositioned within the chamber 356a. The spring/pressure plate 392includes a flat lower face 394 that is positioned adjacent the diaphragm366a, a spring portion 396 that biases the lower face downward, and amounting stem 398 that is friction fit into the wide portion 386 of thepump inlet. In the illustrated embodiment, the spring portion 396 isgenerally circular in configuration and is pre-stressed into a flexedposition by the diaphragm 366a. The natural resiliency of the materialused to construct the spring/pressure plate urges the spring to itsoriginal configuration, thereby biasing the lower face downward toexpand the volume of the chamber 356a. The unitary spring/pressure plate392 may be formed of various suitable materials such as, for example,HYTREL™.

In this embodiment, the valve 364a is a flapper valve that is held inposition on the shoulder 390 of the pump inlet 360a by the top of themounting stem 398. The mounting stem 398 has a cross shaped crosssection which allows the flapper valve 364a to deflect downward intofour open quadrants to allow ink to flow from the ink reservoir into thechamber. The shoulder prevents the flapper valve from deflecting in theupward direction to limit the flow of ink from the chamber back into thereservoir. Rather, ink exits the chamber via the pump outlet 362. Itshould be appreciated that the mounting stem may have a `V` crosssection, an `I` cross section, or any other cross section which allowsthe flapper valve to flex sufficiently to permit the needed flow of inkinto the chamber.

As illustrated in FIG. 38, a conduit 384 joins the pump outlet 362 tothe fluid outlet 328. In the illustrated embodiment, the top wall of theconduit 384 is formed by the lower member of the frame 346, the bottomwall is formed by the body 344 of the chassis, one side is enclosed by aportion of the chassis and the other side is enclosed by a portion ofone of the plastic sheets 350. As illustrated in FIGS. 37 and 38, thefluid outlet 328 is house within a hollow cylindrical boss 399 thatextends downward from the chassis 322. The top of the boss 399 opensinto the conduit 384 to allow ink to flow from the conduit into thefluid outlet. A spring 400 and sealing ball 402 are positioned withinthe boss 399 and are held in place by a compliant septum 404 and a crimpcover 406. The length of the spring 400 is such that it can be placedinto the inverted boss 399 with the ball 402 on top. The septum 404 andcan then inserted be into the boss 399 to compress the spring 400slightly so that the spring biases the sealing ball 402 against theseptum 404 to form a seal. The crimp cover 406 fits over the septum 404and engages an annular projection 408 on the boss 399 to hold the entireassembly in place.

In the illustrated embodiment, both the spring 100 and the ball 402 arestainless steel. The sealing ball 402 is sized such that it can movefreely within the boss 399 and allow the flow of ink around the ballwhen it is not in the sealing position. The septum 404 is formed ofpolyisoprene rubber and has a concave bottom to receive a portion of theball 402 to form a secure seal. The septum 404 is provided with a slit410 so that it may be easily pierced without tearing or coring. However,the slit is normally closed such that the septum itself forms a secondseal. The slit may, preferably, be slightly tapered with-its narrowerend adjacent the ball 402. The illustrated crimp cover 406 is formed ofaluminum and has a thickness of about 0.020 inches. A hole 412 isprovided so that the crimp cover 406 does not interfere with thepiercing of the septum 404.

With the pump and fluid outlet in place, the ink reservoir 324 can befilled With ink. To fill the ink reservoir 324, ink can be injectedthrough the fill port 352. As ink is being introduced into thereservoir, a needle (not shown) can be inserted through the slit 410 inthe septum 404 to depress the sealing ball 402 and allow the escape ofany air from within the reservoir. Alternatively, a partial vacuum canbe applied through the needle. The partial vacuum at the fluid outletcauses ink from the reservoir 324 to fill the chamber 356, the conduit384, and the cylindrical boss 399 such that little, if any, air remainsin contact with the ink. The partial vacuum applied to the fluid outletalso speeds the filling process. Once the ink supply is filled, the plug354 is press fit into the fill port to prevent the escape of ink or theentry of air.

Of course, there are a variety of other methods which might also be usedto fill the present ink supply. In some instances, it may be desirableto flush the entire ink supply with carbon dioxide prior to filling itwith ink. In this way, any gas trapped within the ink supply during thefilling process will be carbon dioxide, not air. This may be preferablebecause carbon dioxide may dissolve in some inks while air may not. Ingeneral, it is preferable to remove as much gas from the ink supply aspossible so that bubbles and the like do not enter the print head or thetrailing tube. To this end, it may also be preferable to use degassedink to further avoid the reaction or presence of bubbles in the inksupply.

Although the ink reservoir 324 provides an ideal way to contain ink, itmay be easily punctured or ruptured and may allow some amount of waterloss from the ink. Accordingly, to protect the reservoir 324 and tofurther limit water loss, the reservoir 324 is enclosed within aprotective shell 330. In the illustrated embodiment, the shell 330 ismade of clarified polypropylene. A thickness of about one millimeter hasbeen found to provide robust protection and to prevent unacceptablewater loss from the ink. However, the material and thickness of theshell may vary in other embodiments.

As illustrated in FIG. 37, the top of the shell 330 has contouredgripping surfaces 414 that are shaped and textured to allow a user toallow a user to easily grip and manipulate the ink supply 320. Avertical rib 416 having a detente 418 formed near its lower end projectslaterally from each side of the shell 330. The base of the shell 330 isopen to allow insertion of the chassis 322. A stop 420 extends laterallyoutward from each side of the wall 358 that defines the chamber 356.These stops 420 abut the lower edge of the shell 330 when the chassis322 is inserted.

A protective cap 332 is fitted to the bottom of the shell 330 tomaintain the chassis 322 in position. The cap 332 is provided withrecesses 428 which receive the stops 420 on the chassis 322. In thismanner, the stops are firmly secured between the cap and the shell tomaintain the chassis in position. The cap is also provided with anaperture 334 to allow access to the pump 326 and with an aperture 336 toallow access to the fluid outlet 328. The cap 332 obscures the fill portto help prevent tampering with the ink supply.

The cap is provided with projecting keys 430 which can identify the typeof printer for which the ink supply is intended and the type of inkcontained within the ink supply. For example, if the ink supply isfilled with black ink, a cap having keys that indicate black ink may beused. Similarly, if the ink supply is filled with a particular color ofink, a cap indicative of that color may be used. The color of the capmay also be used to indicate the color of ink contained within the inksupply.

As a result of this structure, the chassis and shell can be manufacturedand assembled without regard to the particular type of ink they willcontain. Then, after the ink reservoir is filled, a cap indicative ofthe particular ink used is attached to the shell. This allows formanufacturing economies because a supply of empty chassis and shells canbe stored in inventory. Then, when there is a demand for a particulartype of ink, that ink can be introduced into the ink supply and anappropriate cap fixed to the ink supply. Thus, this scheme reduces theneed to maintain high inventories of ink supplies containing every typeof ink.

In the illustrated embodiment, the bottom of the shell 330 is providedwith two circumferential grooves 422 which engage two circumferentialribs 424 formed on the cap 332 to secure the cap to the shell. Sonicwelding or some other mechanism may also be desirable to more securelyfix the cap to the shell. In addition, a label (not shown) can beadhered to both the cap and the shell to more firmly secure themtogether. In the illustrated embodiment, pressure sensitive adhesive isused to adhere the label in a manner that prevents the label from beingpeeled off and inhibits tampering with the ink supply.

The attachment between the shell, the chassis and the cap should,preferably, be snug enough to prevent accidental separation of the capfrom the shell and to resist the flow of ink from the shell should theink reservoir develop a leak. However, it is also desirable that theattachment allow the slow ingress of air into the shell as ink isdepleted from the reservoir to maintain the pressure inside the shellgenerally the same as the ambient pressure. Otherwise, a negativepressure may develop inside the shell and inhibit the flow of ink fromthe reservoir. The ingress of air should be limited, however, in orderto maintain a high humidity within the shell and minimize water lossfrom the ink.

In the illustrated embodiment, the shell 330 and the flexible reservoir324 which it contains have the capacity to hold approximately thirtycubic centimeters of ink. The shell is approximately 67 millimeterswide, 15 millimeters thick, and 60 millimeters high. Of course, otherdimensions and shapes can also be used depending on the particular needsof a given printer.

The illustrated ink supply 320 is ideally suited for insertion into adocking station 432 like that illustrated in FIGS. 44-47. The dockingstation 432 illustrated in FIG. 44, is intended for use with a colorprinter. Accordingly, it has four side-by-side docking bays 338, each ofwhich can receive one ink supply 320 of a different color. The structureof the illustrated ink supply allows for a relatively narrow width. Thisallows for four ink supplies to be arranged side-by-side in a compactdocking station without unduly increasing the footprint of the printer.

Each docking bay 338 includes opposing walls 434 and 436 which defineinwardly facing vertical channels 438 and 440. A leaf spring 442 (FIG.45) having an engagement prong 444 is positioned within the lowerportion of each channel 438 and 440. The engagement prong 444 of eachleaf spring 442 extends into the channel toward the docking bay 338 andis biased inward by the leaf spring. The channels 438 and 440 areprovided with mating keys 439 formed therein. In the illustratedembodiment, the mating keys in the channels on one wall are the same foreach docking bay and identify the type of printer in which the dockingstation is used. The mating keys in the channels of the other wall aredifferent for each docking bay and identify the color of ink for use inthat docking bay. A base plate 446 defines the bottom of each dockingbay 338. The base plate 446 includes an aperture 448 which receives theactuator 340 and carries a housing 450 for the fluid inlet 342.

As illustrated in FIG. 44, the upper end of the actuator extends upwardthrough the aperture 448 in the base plate 446 and into the docking bay338. The lower portion of the actuator 340 is positioned below the baseplate and is pivotally coupled to one end of a lever 452 which issupported on pivot point 454. The other end of the lever 454 is biaseddownward by a compression spring 456 (FIG. 47). In this manner, theforce of the compression spring 456 urges the actuator 340 upward. A cam458 (FIG. 48A) mounted on a rotatable shaft 460 is positioned such thatrotation of the shaft to an engaged position causes the cam to overcomethe force of the compression spring 456 and move the actuator 340downward. Movement of the actuator, as explained in more detail below,causes the pump 326 to draw ink from the reservoir 324 and supply itthrough the fluid outlet 328 and the fluid inlet 342 to the printer.

As illustrated in FIG. 47, a flag 484 extends downward from the bottomof the actuator 340 where it is received within an optical detector 486.The optical detector 486 is of conventional construction and directs abeam of light from one leg 486a toward a sensor (not shown) positionedon the other 486b leg. The optical detector is positioned such that whenthe actuator 340 is in its uppermost position, corresponding to the topof the pump stroke, the flag 484 raises above the beam of light allowingit to reach the sensor and activate the detector. In any lower position,the flag blocks the beam of light and prevents it from reaching thesensor and the detector is in a deactivated state. In this manner, thesensor can be used, as explained more fully below, to control theoperation of the pump and to detect when an ink supply is empty.

As seen in FIG. 45, the fluid inlet 342 is positioned within the housing450 carried on the base plate 446. The illustrated fluid inlet 342includes an upwardly extending needle 462 having a closed, blunt upperend 464, a blind bore 466 and a lateral hole 468. A trailing tube 469,seen in FIG. 47, is connected to the lower end of the needle 462 influid. communication with the blind bore 466. The trailing tube 469leads to a print head (not shown). In most printers, the print head willusually include a small ink well for maintaining a small quantity of inkand some type of pressure regulator to maintain an appropriate pressurewithin the ink well. Typically, it is desired that the pressure withinthe ink well be slightly less than ambient. This back pressure helps toprevent ink from dripping from the print head. The pressure regulator atthe print head may commonly include a check valve which prevents thereturn flow of ink from the print head and into the trailing tube.

A sliding collar 470 surrounds the needle 462 and is biased upwardly bya spring 472. The sliding collar 470 has a compliant sealing portion 474with an exposed upper surface 476 and an inner surface 478 into directcontact with the needle 462. In addition, the illustrated sliding collarincludes a substantially rigid portion 480 extending downwardly topartially house the spring 472. An annular stop 482 extends outward fromthe lower edge of the substantially rigid portion 480. The annular stop482 is positioned beneath the base plate 446 such that it abuts the baseplate to limit upward travel of the sliding collar 470 and define anupper position of the sliding collar on the needle 462. In the upperposition, the lateral hole 468 is surrounded by the sealing portion 474of the collar to seal the lateral hole and the blunt end 464 of theneedle is generally even with the upper surface 476 of the collar.

In the illustrated embodiment, the needle 462 is an eighteen gaugestainless steel needle with an inside diameter of about 1.04millimeters, an outside diameter of about 1.2 millimeters, and a lengthof about 30 millimeters. The lateral hole is generally rectangular withdimensions of about 0.55 millimeters by 0.70 millimeters and is locatedabout 1.2 millimeters from the upper end of the needle. The sealingportion 474 of the sliding collar is made of ethylene propylene timermonomer and the generally rigid portion 476 is made of polypropylene orany other suitably rigid material. The sealing portion is molded with anaperture to snugly receive the needle and form a robust seal between theinner surface 478 and the needle 462. In other embodiments, alternativedimensions, materials or configurations might also be used.

To install an ink supply 320 within the docking bay 338, a user cansimply place the lower end of the ink supply between the opposing walls434 and 436 with one edge in one vertical channel 438 and the other edgein the other vertical channel 440, as shown in FIG. 44. The ink supplyis then pushed downward into the installed position, shown in FIG. 46,in which the bottom of the cap 332 abuts the base plate 446. As the inksupply is pushed downward, the fluid outlet 328 and fluid inlet 342automatically engage and open to form a path for fluid flow from the inksupply to the printer, as explained in more detail below. In addition,the actuator enters the aperture 334 in the cap 332 to pressurize thepump, as explained in more detail below.

Once in position, the engagement prongs 444 on each side of the dockingstation engage the detentes 418 formed in the shell 330 to fully holdflue ink supply in place. The leaf springs 442, which allow theengagement prongs to move outward during insertion of the ink supply,bias the engagement prongs inward to positively hold the ink supply inthe installed position. Throughout the installation process and in theinstalled position, the edges of the ink supply 320 are captured withinthe vertical channels 438 and 440 which provide lateral support andstability to the ink supply. In some embodiments, it may be desirable toform grooves in one or both of the channels 438 and 440 which receivethe vertical rib 416 formed in the shell to provide additional stabilityto the ink supply.

To remove the ink supply 320, a user simply grasps the ink supplying thecontoured gripping surfaces 414, and pulls upward to overcome the forceof the leaf springs 442. Upon removal, the fluid outlet 328 and fluidinlet 342 automatically disconnect and reseal leaving little, if any,residual ink, and the pump 326 is depressurized to reduce thepossibility of any leakage from the ink supply.

Operation of the fluid interconnect, that is the fluid outlet 328 andthe fluid inlet 342, during insertion of the ink supply is illustratedin FIGS. 45 and 46. FIG. 45 shows the fluid outlet 328 upon its initialcontact with the fluid inlet 342. As illustrated in FIG. 45, the housing450 has partially entered the cap 332 through aperture 336, and thelower end of the fluid outlet 328 has entered into the top of thehousing 450. At this point, the crimp cover 406 contacts the sealingcollar 470 to form a seal between the fluid outlet 328 and the fluidinlet 342 while both are still in their sealed positions. This seal actsas a safety barrier in the event that any ink should leak through theseptum 404 or from the needle 462 during the coupling and are couplingprocess.

In the illustrated configuration, the bottom of the fluid inlet and thetop of the fluid outlet are similar in shape. Thus, very little air istrapped within the seal between the fluid outlet of the ink supply andthe fluid inlet of the printer. This facilitates proper operation of theprinter by reducing the possibility that air will enter the fluid outlet328 or the fluid inlet 342 and reach the ink jets in the print head.

As the ink supply 320 is inserted further into the docking bay 338, thebottom of the fluid outlet 328 pushes the sliding collar 470 downward,as illustrated in FIG. 46. Simultaneously, the needle 462 enters theslit 410 and passes through the septum 404 to depress the sealing ball402. Thus, in the fully inserted position, ink can flow from the boss399, around the sealing ball 402, into the lateral hole 468, down thebore 466, through the trailing tube 469 to the print head.

Upon removal of the ink supply 320, the needle 462 is withdrawn and thespring 400 presses the sealing ball 402 firmly against the septum toestablish a robust seal. In addition, the slit 410 closes to establish asecond seal, both of which serve to prevent ink from leaking through thefluid outlet 328. At the same time, the spring 472 pushes the slidingcollar 470 back to its upper position in which the lateral hole 468 isencased within the sealing portion of the collar 474 to prevent theescape of ink from the fluid inlet 342. Finally, the seal between thecrimp cover 406 and the upper surface 476 of the sliding collar isbroken. With this fluid interconnect, little, if any, ink is exposedwhen the fluid outlet 328 is separated from the fluid inlet 342. Thishelps to keep both the user and the printer clean.

Although the illustrated fluid outlet 328 and fluid inlet 342 provide asecure seal with little entrapped air upon sealing and little excess inkupon unsealing, other fluid interconnections might also be used toconnect the ink supply to the printer. For example, the illustratedfluid inlet could be located on the ink supply and the illustrated fluidoutlet could be located in the docking bay.

As illustrated in FIG. 46, when the ink supply 320 is inserted into thedocking bay 338, the actuator 340 enters through the aperture 334 in thecap 332 and into position to operate the pump 326. FIGS. 48A-Eillustrate various stages of the pump's operation. FIG. 48A illustratesthe fully charged position of the pump 326. The flexible diaphragm 366is in its lowermost position, the volume of the chamber 356 is at itsmaximum, and the flag 484 is blocking the light beam from the sensor.The actuator 340 is pressed against the diaphragm 366 by the compressionspring 456 to urge the chamber to a reduced volume and create pressurewithin the pump chamber 356. As the valve 364 limits the flow of inkfrom the chamber back into the reservoir, the ink passes from thechamber through the pump outlet 362 and the conduit 384 to the fluidoutlet 328. In the illustrated embodiment, the compression spring ischosen so as to create a pressure of about 1.5 pounds per square inchwithin the chamber. Of course, the desired pressure may vary dependingon the requirements of a particular printer and may vary throughout thepump stroke. For example, in the illustrated embodiment, the pressurewithin the chamber will vary from about 90-45 inches of water columnduring the pump stroke.

As ink is depleted from the pump chamber 356, the compression spring 456continues to press the actuator 340 upward against the diaphragm 366 tomaintain a pressure within the pump chamber 356. This causes thediaphragm to move upward to an intermediate position decreasing thevolume of the chamber, as illustrated in FIG. 48B. In the intermediateposition, the flag 484 continues to block the beam of light fromreaching the sensor in the optical detector 486.

As still more ink is depleted from the pump chamber 356, the diaphragm340 is pressed to its uppermost position, illustrated in FIG. 48C. Inthe uppermost position, the volume of the chamber 356 is at its minimumoperational volume and the flag 484 rises high enough to allow the lightbeam to reach the sensor and activate the optical detector 486.

The printer control system (not shown) detects activation of the opticaldetector 486 and begins a refresh cycle. As illustrated in FIG. 48D,during the refresh cycle the cam 458 is rotated into engagement with thelever 452 to compress the compression spring 456 and move the actuator340 to its lowermost position. In this position, the actuator 340 doesnot contact the diaphragm 366.

With the actuator 340 no longer pressing against the diaphragm 366, thepump spring 370 biases the pressure plate 368 and diaphragm 366 outward,expanding the volume and decreasing the pressure within the chamber 356.The decreased pressure within the chamber 356 allows the valve 364 toopen and draws ink from the reservoir 324 into the chamber 356 torefresh the pump 326, as illustrated in FIG. 48D. The check valve at theprint head, the flow resistance within the trailing tube, or both willlimit ink from returning to the chamber 356 through the conduit 384.Alternatively, a check valve may be provided at the outlet port, or atsome other location, to prevent the return of ink through the outletport and into the chamber.

After a predetermined amount of time has elapsed, the refresh cycle isconcluded by rotating the cam 458 back into its disengaged position andthe ink supply typically returns to the configuration illustrated inFIG. 48A.

However, if the ink supply is out of ink, no ink can enter into the pumpchamber 356 during a refresh cycle. In this case, the back pressurewithin the ink reservoir 324 will prevent the chamber 356 fromexpanding. As a result, when the cam 458 is rotated back into itsdisengaged position, the actuator 340 returns to its uppermost position,as illustrated in FIG. 48E, and the optical detector 486 is againactivated. Activation of the optical detector immediately after arefresh cycle, informs the control system that the ink supply is out ofink (or possibly that some other malfunction is preventing the properoperation of the ink supply). In response, the control system cangenerate a signal informing the user that the ink supply requiresreplacement. This can greatly extend the life of the print head bypreventing dry firing of the ink jets.

In some embodiments in may be desirable to rotate the cam 458 to thedisengaged position and remove pressure from the chamber 356 wheneverthe printer is not printing. It should be appreciated that a mechanicalswitch, an electrical switch or some other switch capable of detectingthe position of the actuator could be used in place of the opticaldetector.

The configuration of the present ink supply is particularly advantageousbecause only the relatively small amount of ink within the chamber ispressurized. The large majority of the ink is maintained within thereservoir at approximately ambient pressure. Thus, it is less likely toleak and, in the event of a leak, can be more easily contained.

The illustrated diaphragm pump has proven to be very reliable and wellsuited for use in the ink supply. However, other types of pumps may alsobe used. For example, a piston pump, a bellows pump, or other types ofpumps might be adapted for use.

As discussed above, the illustrated docking station 432 (FIG. 44)includes four side-by-side docking bays 338. This configuration allowsthe wall 434, the wall 436 and the base plate 446 for the four dockingbays to be unitary. In the illustrated embodiment, the leaf springs foreach side of the four docking bays can be formed as a single piececonnected at the bottom. In addition, the cams 458 for each dockingstation are attached to a single shaft 460. Using a single shaft resultsin each of the four ink supplies being refreshed when the pump of anyone of the four reaches its minimum operational volume. Alternatively,it may be desirable to configure the cams and shaft to provide a thirdposition in which only the black ink supply is pressurized. This allowsthe colored ink supplies to remain at ambient pressure during a printjob that requires only black ink.

The arrangement of four side-by-side docking bays is intended for use ina color printer. One of the docking bays is intended to receive an inksupply containing black ink, one an ink supply containing yellow ink,one an ink supply containing cyan ink, and one an ink supply containingmagenta ink. The mating keys 439 for each of the four docking bays aredifferent and correspond to the color of ink for that docking bay. Themating keys 439 are shaped to receive the corresponding keys 430 formedon a cap of an ink supply having the appropriate color. That is, thekeys 430 and the mating keys 439 are shaped such that only an ink supplyhaving the correct color of ink, as indicated by the keys on the cap,can be inserted into any particular locating bay. The mating keys 439can also identify the type of ink supply hat is to be installed in thedocking bay. This system helps to prevent a user from inadvertentlyinserting an ink supply of one color into a docking bay for anothercolor or from inserting an ink supply intended for one type of printerinto the wrong type of printer.

Constant pressurization of the various ink supply cartridges describedhas the following advantages over intermittent pressurization:

(1) Lower product cost/minimum product complexity by eliminating anypump station;

(2) Pressurizing the tubes reduces or eliminates air diffusion intotubes (depending on pressure level).

Intermittent pressurization has the following advantages over constantpressurization:

(1) Fluid seals and valves do not have to withstand constant pressure,resulting in improved reliability;

(2) Ink supplies are less expensive, since the plastic shell does notneed to be as strong.

Conclusion

The various print cartridges (for example down connect needle, upconnect needle, and septum tower), carriages, and off-axis ink deliverysystems described herein may be used in various combinations to provideink to the nozzles of the printheads in the print cartridges. As oneexample, any of the print cartridges described may be used with eitherthe pressurized or unpressurized ink supply cartridges. The ink supplycartridges may be arranged in a printer for convenient access, ease ofuse, maximum utilization of space, and allowing for the requireddelivered ink volume. The pressure regulator, being integral with theprint cartridge in the preferred embodiment, allows printheadperformance to be independent of the relative heights of the ink supplyand printhead.

The lowest cost system will typically be one with unpressurizedsupplies. However, pressurization may be required for some situations.This is best understood by considering causes of dynamic and staticpressure changes. The static pressure in the printhead is defined asthat which exists when the printhead is parked and not operating and istypically optimally set to -2 to -6 inches of water column by the springin the regulator. However, if the ink supplies are located more than 6inches below the printhead, then the regulator will always be open(assuming the above setpoint range), and the static pressure will alwaysbe the difference in height. To make matters worse, the pressure ofconcern is dynamic, defined as the pressure experienced in the printheadduring operation. Thus, the actual dynamic pressure will be an evenlarger negative number and will be outside the regulator range.

Pressurizing the ink supply will solve this problem. This can be done bythe aforementioned method or by using springs to provide constant inksupply pressure. This can be done to counteract the relative heights,and other factors that affect the dynamic pressure drop. Factors thatincrease the dynamic pressure drop include rate of ink usage by theprinthead, decreasing tubing diameter, increasing tubing length, andincreasing ink viscosity. The pressurization must be increased until thepressure is entirely controlled by the regulator to within the printquality driven pressure specification.

As a result of these design options, the integral pressure regulatoroffers a wide range of product implementations other than thoseillustrated in FIGS. 1A and 1B. For example, such ink delivery systemsmay be incorporated into an inkjet printer used in a facsimile machine500 as shown in FIG. 49, where a scanning cartridge 502 and an off-axisink delivery system 504, connected via tube 506, are shown in phantomoutline.

FIG. 50 illustrates a copying machine 510, which may also be a combinedfacsimile/copying machine, incorporating an ink delivery systemdescribed herein. Scanning print cartridges 502 and an off-axis inksupply 504, connected via tube 506, are shown in phantom outline.

FIG. 51 illustrates a large-format printer 516 which prints on a wide,continuous paper roll supported by tray 518. Scanning print cartridges502 are shown connected to the off-axis ink supply 504 via tube 506.

Facsimile machines, copy machines, and large format machines tend to beshared with heavy use. They are often used unattended and for largenumbers of copies. Thus, large capacity (50-500 cc) ink supplies willtend to be preferred for these machines. In contrast, a home printer orportable printer would be best with low capacity supplies in order tominimize product size and cost. Thus, the product layouts shown in FIGS.1A and 1B are most appropriate for such smaller form factor or lowercost applications.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made within departing from thisinvention in its broader aspects and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit and scope of this invention.

What is claimed is:
 1. A printing system comprising:a first inkreservoir; a scanning carriage; a print cartridge for installation insaid carriage, said print cartridge having a second ink reservoirinternal to said print cartridge, said print cartridge containing apressure regulator comprising:a valve for controlling an opening in anink path between said first ink reservoir and said second ink reservoir;a flexible member within said print cartridge maintained at an internalreference pressure, said flexible member expanding or contractingdependent upon the relative pressures internal and external to saidflexible member; and an actuator in contact with said flexible memberfor actuating said valve based on the expansion and contraction of saidflexible member, said valve controlling a flow of ink into said secondink reservoir such that ink is supplied to a printhead within said printcartridge at a substantially constant pressure.
 2. The system of claim 1wherein said flexible member comprises two flexible bags maintained atsaid internal reference pressure and having a common direction ofexpansion and contraction, and wherein said actuator comprises aregulator lever which directly bears against at least one of said bagsand thereby actuates said valve, said regulator lever having an axis ofrotation perpendicular with said direction of expansion and contractionof said bags so that said lever tracks any expansion and contraction ofsaid bags.
 3. The system of claim 2 further comprising an accumulatorlever that applies a substantially constant force against said referencepressure in said bags, said accumulator lever having an axis of rotationapproximately perpendicular to said direction of expansion andcontraction of said bags so that said accumulator lever tracks anyexpansion and contraction of said bags.
 4. The system of claim 3 whereinone of said bags has a region of enhanced sensitivity to differentialpressure across said region, and said region bears against saidregulator lever.
 5. The system of claim 4 wherein the other of said bagshas a region of enhanced sensitivity to differential pressure acrosssaid region, and said region bears against said accumulator lever. 6.The system of claim 2 wherein each of said bags has a region of enhancedsensitivity to differential pressure across said region, and each ofsaid region bears against the other.
 7. The system of claim 2 whereinsaid valve has a resiliently deformable valve seat such that saidactuator, valve, and valve seat compensate for air expansion within saidprint cartridge.
 8. The system of claim 1 further comprising a conduithaving a flexible portion, said conduit fluidically coupling said firstink reservoir to said valve.
 9. The system of claim 8 further comprisingan engageable fluid connection between said print cartridge and saidconduit, said fluid connection scanning with said carriage.
 10. Thesystem of claim 8 further comprising an engageable fluid connectionbetween said print cartridge and said conduit, said fluid connection notscanning with said carriage.
 11. The system of claim 9 wherein saidfluid connection comprises a first interconnect member being a resilientseptum, and a second interconnect member being a hollow needle.
 12. Asystem of claim 1 wherein said ink reservoir within said print cartridgehas a negative internal pressure relative to ambient pressure.
 13. Anink delivery system supported on a rigid frame, in which a printheadmounted on a carriage moves relative to the frame across a print zone todeposit ink on media, with the printhead incorporated into a cartridgewhich has an internal pressure regulator that supplies ink to theprinthead, said system comprising:an off-carriage ink supply within ahousing that is adapted to be removably mounted to a supply station; anink reservoir in said ink supply that is in fluid communication with adischarge port; and ink contained in the ink reservoir which passes outof the discharge port, through a conduit, and then to the regulator, theregulator having a valve that opens and closes in response to an inkpressure in the cartridge, the ink reservoir and the valve operativelycoupled to maintain the cartridge pressure at a chosen setpoint betweenzero and -25 inches of water when the ink supply is removably mounted tothe supply station.
 14. The system of claim 13 wherein the dischargeport comprises a septum.
 15. The system of claim 14 wherein thedischarge port further comprises a spring-loaded sealing member.
 16. Thesystem of claim 13 wherein the discharge port comprises a spring-loadedsealing member.
 17. The system of claim 13 wherein the regulatorcomprises:a flexible member with a reference surface and a reservoirsurface, the reference surface in fluid communication with an outsideatmosphere and the reservoir surface in fluid communication with an inkchamber within said cartridge; and an actuator adjacent to the flexiblemember for actuating the valve based upon a differential pressurebetween the outside atmosphere and the ink chamber.
 18. The system ofclaim 17 wherein the valve comprises a nozzle and a valve seat, thenozzle having a tapered geometry for reducing the area of contactbetween the nozzle and the valve seat when the valve is closed.
 19. Thesystem of claim 17 wherein the actuator includes a lever pivotallymounted for rotation about an axis, wherein the valve includes a valveseat and a nozzle, and wherein the valve seat is mounted on the lever.